Mostly going to do PvE, dungens, raids etc.
(Alliance and Horde)
For horde Troll cba Beast Slayer and the Troll Berserk
PvP Night Elf you can pounch when shadowmeld and 2% extra avoidance
Tauren stun is nice to have
Also aoe wise.
If you're alliance, then hit Worgen.
and if you intend to tank; nelf > every other race in wow. static +2% miss chance is the most powerful racial passive (for tank)
the rest is not so good ;D
Worgen - 1% crit is primarily best for DPS, but it can also help you to maintain threat and increase the amount of Savage Defense procs. The Nature and Shadow resistance racial is more commonly useful than the Night Elf's Nature resistance-only racial. Gotta low the sprint ability aswell - 40% increased movement speed for 10 seconds? Yummy.
Night Elf - 2% less chance to be hit is amazing for tanks, probably the most useful druid tank racial at this point in the game. It could help out DPSers too, especially in PvP and in a smaller part PvE. Nature resistance is helpful regardless of if you're a tank or a DPS, situational, but helpful.
Tauren - Increased health is always tasty no matter what you do. Tauren also have a Nature resistance passive. War Stomp's stun is very situational, but I can think of at least a few boss fights were it can save your raid from a certain wipe.
Troll - 20% increased attack speed for 10 sec is like a smaller version of Heroism, extremely useful and advised to use whenever it's off CD. Regeneration helps in both PvP and PvE, but it is a very miniscule amount so I can't really tell you exactly how useful it is.
Night Elf for Alliance in regard to Feral Tanking.
Troll for Horde in regard to Feral DPS,
Tauren for Horde in regard to Feral Tanking.